The present invention relates generally to an emission spectroscopic processing apparatus for spectrally separating radiation emitted from a plasma or the like into component spectra, converting the component spectra having respective wavelengths into electric signals by means of associated light receiving elements, respectively, and obtaining a desired detection output by processing the signals. Further, the present invention relates to a plasma processing method using the emission spectroscopic processing apparatus.
The emission spectroscopic processing apparatus for spectrally separating radiation emitted from a plasma or the like into component spectra, converting the component spectra having respective wavelengths into electric signals by means of light receiving elements or devices and obtaining a desired detection output by processing the signals has been known heretofore. By way of example, a process monitoring apparatus adopting a main component analysis process mentioned below is disclosed, for example, in European Patent No. 1089146.
More specifically, electromagnetic radiation emitted from a plasma camber is inputted into a process monitoring apparatus which is composed of a spectrometer and a processor through the medium of an optical fiber or the like. The spectrometer mentioned above is designed to spatially split or separate the electromagnetic radiation of plasma on the basis of the wavelengths by using, for example, a prism or a diffraction grating. Subsequently, a plurality of spatially separated spectra of respective wavelengths are detected by means of e.g. a CCD (Charge Coupled Device) array of 2048 channels, whereby a detection signal, i.e., OES (Optical Emission Spectroscopic) signal is generated. The OES signal is then digitized through e.g. an analogue-to-digital (A/D converter) to be outputted to a processor for undergoing further processings. In this manner, the electromagnetic radiation emitted from a plasma is measured by the spectrometer and supplied to the processor in the form of the OES signal of 2048 channels.
Main or major component analysis process of a specific or desired type to be executed by the processor is selected by means of a remote computer system, fabrication equipment or the like. In place of the spectrometer, there may be employed a diffraction grating, prism, optical filter or other type of wavelength selecting device(s) in combination with a plurality of detectors (e.g. photodiodes, photo multipliers or the like) to thereby supply the information concerning a plurality of electromagnetic radiation wavelengths to the processor. In this conjunction, it is to be added that the processor is coupled to a plasma etching controller by way of a control bus.